Rotary engines and pumps

ABSTRACT

The engine provides a rotary engine or pump of the type comprising a body with an internal epitrochoidal cross-section chamber and a triangular cross-section rotor rotatable in the body chamber so as to form a plurality of working chambers that vary in volume upon relative rotation of the rotor and the body. A new guidance means for guiding the rotor in the required motion relative to the body comprise a first planar guide surface of essentially triangular shape movable with the rotor and a second planar guide surface movable with the body, the guide surfaces being in relatively-sliding engagement with one another, the said second surface being of oval shape generated by the said first surface in their required relative motion. A seal for use between each rotor apex and the chamber wall comprises two cooperating seal members urged radially outwards by operating fluid of the mechanism.

[ Nov. 18, 1975 ROTARY ENGINES AND PUMPS I [76] Inventor: Herbert LewisGray, 54 Main St.,

Milton, Ontario, Canada [22] Filed: Oct. 9, 1974 [21] Appl. No,: 513,446

Related US. Application Data [62] Division of Ser. N0. 414,000, Nov. 8,1973, Pat. NO.

[52] US. Cl. 418/87; 418/91; 418/117; 1 418/124 [51] Int. CL? F01C19/02; F04C 27/00; F01C 21/04 [58] Field of Search 418/91, 93, 87, 113,117, 418/122-124, 267, 268

[56] References Cited UNITED STATES PATENTS Mapes 418/117 1,224,0899/1966 Germany ..4l8/l24 Primary Examiner-John J. Vrablik [57] ABSTRACTThe engine provides a rotary engine or pump of the type comprising abody with an internal epitrochoidal cross-section chamber and atriangular cross-section rotor rotatable in the body chamber so as toform a plurality of working chambers that vary in volume upon relativerotation of the rotor and the body. A new guidance means for guiding therotor in the required motion relative to the body comprise a firstplanar guide surface of essentially triangular shape movable with therotor and a second planar guide surface movable with the body, the guidesurfaces being in relatively-sliding engagement with one another, thesaid second surface being of oval shape generated by the said firstsurface in their required relative motion. A sea] for use between eachrotor apex and the chamber wall comprises two cooperating seal membersurged radially outwards by operating fluid of the mechanism.

5 Claims, 16 Drawing Figures US. Patent Nov. 18,1975 Sheet1of4 3,920,359

Sheet 2 of 4 3,920,359

US. Patent Nov. 18, 1975 Nov. 18, 1975 Sheet 3 of4 3,920,359

U.S. Patent US. Patent Nov. 18,1975 Sheet40f4 3,920,359

u k LukoQ m ROTARY ENGINES AND PUMPS CROSS REFERENCE TO RELATEDAPPLICATION This application is a division of my application Ser.

No. 414,000 filed Nov. 8, 1973, now US. Pat. No.

FIELD OF THE INVENTION REVIEW OF THE PRIOR ART Of the very large numberof rotary engines that have been proposed hitherto only one has at thistime achieved any substantial commercial success, namely that known asthe Wankel rotary engine, as described, for example, in US. Pat. No.2,988,065, issued June 13, 1961 to N.S.U. Motorenwerke AC. and WankelG.m.b.I-l., and also in the book The Wankel Engine by Jan P. Norbye,published 1971 by Chelton Book Co., Library of Congress Catalogue CardNO: 73-161624.

The most usual form of Wankel engine consists of one or more three-lobedtriangular cross-section r tors, each mounted for orbital motion withina twolobed epitrochoidal cross-section chamber in the en gine casing.The rotor rotates freely by means of an interposed bearing upon aneccentric portion of a main output shaft, this eccentric mounting beingessential so that the rotor can exert the necessary torque on themainshaft. Other lobe combinations can theoretically be used, but theone outlined appears to have been universally adopted.

Because of this eccentric mounting the rotor moves within the chamber inwhat is usually described as an orbital motion, which may be regarded asa combination of circular and pulsating motions of the rotor.

The rotatin of the rotor on its bearing must be phased accurately withits motion in the chamber in order to provide a plurality of workingchambers that vary in volume in the required manner upon relativerotation of the rotor and chamber. The current practice with theWankel-type engine as described in the Wankel specification, thedisclosure of which is incorporated herein by reference, is to providethe necessary phasing by means of an internal-toothed ring gear rigidlyattached to the rotor meshing with a pinion reaction gear rigidlyattached to the casing. With said universally adopted lobe configurationif the ring gear has 72 teeth then the reaction gear must have 48 teethto produce a 3:2 ratio between them.

Among the problems encountered with the Wankel engine has been coolingof the rotor, and the solution often adopted has been to provide heattransfer to an external radiator by means of controlled pressurecirculation of oil to and from the rotor. An arrangement for circulatingcooling oil within the rotor interior is described and claimed in US.Pat. No. 3,102,683, issued Sept. 3, 1963 to N.S.U. Moterenwerke A.G. andWankel G.m.b.H. In the disclosed arrangement oil is fed to a chamberwithin the rotor interior where it performs its intended coolingfunction. The oil is distributed by centrifugal forces around theinterior surface of this chamber in the form of a film thereof, and theoil is removed from the chamber while the thickness of this film ismaintained at a constant value by the provision of a stationary discwhich extends into the chamber. The shape of the disc peripherycorresponds to the FIGURE swept by the oil-receiving rotor internalchamber with provisions for maintaining the said oil film thickness, thedisc having radially extending channels with openings that intercept theoil, so that it is forced through the openings into the channels and conveyed to another part of the engine (e.g. the casing and/or a cooler.)

Another problem encountered with rotary engines of the type disclosed inthe above-mentioned US. Pat. No. 2,988,065 and discussed therein (column15, lines 11-46) is that the angle between the rotor apex seals and theepitrochoidal body surface which they contact must be less than 40 orthere is a danger of jamming of the seals between the rotor and thesurface. In Norbyes book the preferred value is given as 30.

DEFINITION OF THE INVENTION It is an object of the invention to providea new rotor apex seal for use in a rotary engine or pump.

In accordance with the present invention there is provided in a rotarymechanism comprising a body providing an internal chamber having aninternal peripheral surface and a lobed rotor mounted within the chamberfor rotation within the chamber with a plurality ofcircumferentially-spaced apex portions in sealing engagement with thesaid chamber internal surface, a seal for interposition between arespective apex portion and the chamber internal surface, each sealcomprising two axially-extending abutting seal members mounted inrespective axially-extending slots in the apex portion, each seal memberbeing operative as a piston within its respective slot as a cylinder,means for supplying to the leading seal member operative fluid from therespective rotor trailing face, and for supplying to the trailing sealmember operative fluid from the respective rotor leading face, thesupply of fluid to each seal member urging the respective seal memberradially outwardly from the rotor into engagement with the chamberinternal surface and into engagement with the other seal member tooppose the fluid pressure thereon from the chamber.

Also in accordance with the invention there is provided in a rotarymechanism comprising a body providing an internal chamber having aninternal peripheral surface and a blobed rotor mounted within thechamber for rotation within the chamber with a plurality ofcircumferentially-spaced apex portions in sealin'g engagement with thesaid chamber internal surface, a seal for interposition between arespective apex portion and the chamber internal surface, each sealcomprising two axially-extending abutting seal members mounted inrespective axially-extending slots in the apex portion, wherein meansfor supplying lubricating fluid to the said seal comprises a passageleading from the rotor interior to a space between the abutting sealmembers and a ball valve disposed in the said passage, the valve beingoperative under the effect of centrifugal force thereon to open andpermit flow of lubricating fluid to the said space also under the effectof centrifugal force, and being operative under the effect ofcentripetal force thereon to close and obstruct flow of lubricatingfluid from the said space also under the effect of centripetal force.

DESCRIPTION OF THE DRAWINGS Particular preferred embodiments of theinvention will now be described, by way of example, with reference tothe accompanying diagrammatic drawings, wherein:

FIG. 1 is an exploded view of one rotary mechanism operable as a motoror pump, the mechanism being shown exploded along the axis of rotationof the mainshaft thereof,

FIGS. 2 to 5 are schematic cross-sectional views on the line 2-2 of FIG.1 to show the different positions that can be taken by the rotorrelative to the chamber in which it is located, and the correspondingpositions relative to the members constituting the guidance means,

FIG. 6 is a cross-section view on the line 66 of FIG. 2 and showing themechanism in assembled condition,

FIG. 7 is a cross-sectional view through one of the rotor apices,perpendicular to the axis of rotation thereof, in order to show detailof the construction of the apex seals employed with the rotor,

FIGS, 8 and 9 are schematics of internal epitrochoidal paths in order toshow certain limits in the geometry of the path that can be used, and

FIGS. 10 to 16 are graphs comparing the characteristics of known rotaryengines with those that can be produced employing the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As indicated above the rotarymechanism illustrated herein very schematically as a particularpreferred embodiment may be employed as an engine or a compressor and,depending upon the particular application, will require certainadditional equipment (such as a carburettor, oil-cooler, etc.) whosedescription is omitted since it is not essential for full illustrationand understanding of the present invention. The nature andcharacteristics of such additional equipment required will be apparentto those skilled in the art.

The mechanism consists of an outer casing indicated generally by thereference 10 and constituted by a peripheral part 12 and two end plates14 and 16 fastened thereto by any suitable means, for example, bythrough-bolts 17. The casing provides an internal chamber 18 whoseinternal periphery 20 is symmetrical about a central longitudinal axis22, the said periphery being of two-lobed epitrochoidal cross-sectionperpendicular to the axis 22. Bearings 24 in the end plates support amainshaft 26 for rotation about an axis coincident with the axis 22. Theshaft is provided with an eccentric portion 28 which is integraltherewith or rigidly attached thereto, the eccentric portion being ofcircular cross-section perpendicular to a longitudinal axis 30, which isparallel to the axis 22 and spaced a distance r (FIG. 6) therefrom. Thisdistance r is the effective eccentricity of the mechanism.

A three-lobed rotor indicated generally by the reference 32 is mountedby bearing part 34 for free rotation on the shaft eccentric portion 28,so that it can move in the so-called orbital or planetary motion withinthe chamber 18 as the shaft rotates. The rotor 32 is of hypotrochoidalcrosssection having an external periphery constituted by three sidewalls 36 meeting at three corresponding apices 38, each apex beingprovided with a corresponding apex seal indicated generally by thereference 40. These seals are omitted from FIGS. 2

to 6 for simplicity of illustration. The external periphery of the rotoris of general equilateral triangle crosssection perpendicular to itsaxis 30 and symmetrical about that axis, the sidewalls 36 being howeverslightly arcuate radially outwards and not straight. Working fluid canbe introduced into the part of the chamber 18 not occupied by the rotorvia an inlet 42 in the end plate 14 and removed via an outlet 43 in themember 14. The mechanism is also illustrated as comprising an ignitiondevice 44 mounted in a corresponding opening 45, although other forms ofdevice, or other ignition means (e. g. when the mechanism is a dieselengine) can be employed. Suchya device is of course not required whenthe mechanism is a pump.

The structure so far described is also the basic structure of the Wankelrotary engine. As the rotor moves in its orbital motion a plurality ofworking chambers are formed between the walls 20 and 36 that varycyclically in volume. The operation of the device either as an engine oras a compressor is now so well known as not to require furtherdescription. In the Wankel engine however the rotor and main shaft areprovided respectively with an internally-toothed ring gear and anexternally-toothed pinion gear that mesh with one another, the piniongear being fixed to the end plate coaxially with and surroundiing themainshaft, and thereby serve to phase or register the position of therotor with respect to the inner peripheral surface 20 as the rotor movesin its orbital motion.

This gearing has the function of rotating the centre of mass of therotor in a circular path of radius r and at twice the mean angularvelocity of the rotor apices, reacting against the inertial forces ofthe rotor and thereby taking the positioning load that would otherwisebe applied to the apex portions of the rotor.

In a mechanism in accordance with the invention the necessary guideconnection between the rotor and the casing 10, in order to ensure thatthe rotor is guided in the required motion relative to the casing, isproduced by two continuous freely relatively-sliding bearing guidesurfaces 46 and 48 provided respectively on the casing and rotor. Inthis particular embodiment the rotor guide surface 48 is constituted bythe inner periphery of a recess 50 in one side wall of the rotor, whilethe casing guide surface 46 is provided by the external periphery of acore guide member 52 fixed to the end plate 14 and protruding into therecess 50. The surfaces 46 and 48 are symmetrical about their respectiveaxes and one of them must be the minimum boundary figure that iscircumscribed by the other in the required orbital motion of the rotorwithin the casing. It is also an essential condition that one of thesurfaces shall be shaped to conform to a specific mathematical curvewhich will result in a two-lobed oval-like form for that surface, sothat the two co-operating guide surfaces will be operative to providethe necessary restraint and guidance between the relatively movableparts.

The rotor internal guide surface 48 has the form of an equilateraltriangle contained within the shape of the rotor external periphery. Itis then found that the corresponding casing second oval guide surface 46of the core guide member has its major and minor axes parallelrespectively to the minor and major axes of the casing epitrochoidalsurface 12 and functions as a cam, as will be described in greaterdetail below. Side seals (not shown) will be provided which co-operatewith the apex seals to seal off the variable-volume working chambersfrom one another and from the remainder of the chamber 18. Theconstruction of such side seals will be known to those skilled in theart.

A recess 51 similar to the recess 50 is provided in the other rotor sidewall for balance, but may instead or in addition provide a guideconnection surface.

FIGS. 2 and 5 show some of the different relative positions that areoccupied by the rotor in the chamber 18 (one of the lobes beingindicated by a dot so that its movements are more easily followed) andthe corresponding relative positions occupied by the core guide surface46 in engagement with rotor guide surface 48.

' It is difficult to make drawings at this small scale which will allowillustration of the exact relation of the guide surfaces 46 and 48 to bevisually observed, since the clearances obtained frequently are verysmall. To facilitate explanation of the actual sequence of events, I usethe term indexing to indicate that three places on surface 48 are incontact with surface 46, while l use the term guiding to imply that onlytwo such places of contact exist. Small circles shown on the rotor faceare indicators of the contact place locations. Thus in the relativepositions illustrated by FIGS. 2 and 5 where there are three contactpoints the rotor is controlled by indexing, while in all other positionsthere are only two contact points and the rotor is controlled by guidingin its dynamic motion. In both control modes rotor stability ispreserved. Since the shape of the continuous surface 46 is thatgenerated by the movement of the continuous surface 48 in the requiredmotion, then the rotor is constrained to follow only that motion,resulting in an ordered sequence of relative sliding motion between thetwo engaged surfaces, in which zero sliding or even some retrogressionis possible during the operation of the engine or compressor.

One of the essential parameters to be considered for rotory mechanism ofthe type to which this invention applies is known as the K factor, whichis the ratio 2r /r where 2r is the maximum rotor or stator radius and ris the eccentricity thereof. I will show that rotary engines previouslyproposed have operated with K values for the chant er of greater than 6,usually about 7, while I am able with my invention to provide a K valuepreferably of 5, which will be shown to have very substantial designadvantages.

The apex seals 40 are required to provide the necessary sealing underthe extremely arduous conditions encountered in a rotary engine, and thedevelopment of such seals has been crucial in the production of acommercially acceptable engine. 1

The problem of designing an engine with an acceptable apex seal anglehas been mentioned above, and this problem becomes more acute withreduction in K value of the chamber, being particularly difficult tosolve for K values less than 7.

FIG. 7 shows in cross-section a particularly advantageous seal structurewherein two axially-extending seal members 54, which can be described asof boomerang transverse cross-section, have their two immediatelyadjacent faces abutting one another, with corresponding outer end partsextending radially from the rotor and with corresponding inner end partsthereof engaged in a respective axially-extending longitudinal slot 56.The inner-most edge of each member 54 is provided with a suitable gasseal 57 and gas-conveying passages 58 lead from an opening 59 in arespective rotor face 36 to the bottom of the opposite slot so that eachmember 54 will operate as a piston within its respective slot as acylinder.

If it is assumed for example that the rotor is rotating clockwise seenin FIG. 2, then the surface 36a is the leading" surface with respect toits associated seal. The pressurized gas in the respective workingchamber will flow through the respective passage 58a to the con-' nectedslot 56a and force the seal member 54a radially outwards in its slot inthe direction to press against the other seal member 54b in oppositionto the gas pressure thereon, and to thereby reduce, or at leastmaintain, the leaning angle (ie the angle of inclination of the seal tothe stator wall) at a predetermined value. Assuming that the gases atthe face 36a are the expanded igniting gases then as the seal passesover the cusp of the casing epitrochoidal inner wall, the gases will nowbe exhausted from the passage 580 by the engine exhaust action whilepressurized gas will be applied through the passage 56b, reversing thedirection of the gas action on the seal, and causing the seal member 54bto be pushed outwardly to press against the seal member 54a.

As mentioned above in US. Pat. No. 2,988,065 Wankel specified a desiredapex seal angle of less than 40, while Norbye mentions that a practicalupper limit is 3.0". It can be shown that for a rotary engine of chamberK value 5 a single vertical seal would have a maximum leaning angle ofabout 37; a seal in accordance with the invention is operable withangles no greater than 22.

The seal is lubricated automatically by means of a ball valve 60operative in a radial bore 62 and connecting a space 64 between theabutting seal member faces with the interior space 66 of the rotor.During portions of the rotor motion centrifugal force will be effectiveto forceoil through the passage 62 past the open ball valve to the space64 and thence between the seal members 54; upon reversal of the forceduring other parts of the motion the ball valve closesto preventdrainage of oil from the space 64.

In the interest of establishing a valid basis for comparison of myguidance means with existing means it is necessary to consider themathematical foundation which supports each of them.

It is possible to avoid misunderstanding which may occur when differentK factors are used for designing the guidance means and fixing the sizeof the rotor. The analysis is no less general in its conclusion byapplying the simplifying condition that the same K factor is assumed toapply.

The geometry of the epitrochoid is elaborated in Norbyes book, and hisstatement of the necessary ratio of the annular ring gear to thereaction pinion gear of 3:2, has also been mentioned earlier. Bygeometeric construction the annular gear has a radius r and the reactiongear radius r r and their necessary relation results in the equality;

In a three-lobed rotor based on an, equilateral triangle the length ofthe longest radius must always be twice that of shortest radius r andsince K 2r,/r,. the above result is that K 6.

A requirement I believe that must be met in practice is illustrated byFIGS. 8 and 9, which show the internal epitrochoidal paths generated bythe short radius of the rotor triangle at its point of intersection withthe midpoint of one side of the rotor triangle for two different raiosof a and b, where a is the major axis and b is the minor axis. With theprior art gear indexing means the reversal of motion indicated by FIG. 7cannot take place, since it would involve retrogression of the pinion inits engagement with the ring gear, and would result in jamming or evenstripping thereof. The motion illustrated by FIG. 8 is therefore alimiting condition for a Wankel type engine, establishing the relationthat must be satisfied in the design of this ring gear and pinion,

since a/b (r r,.)/(r, r.) 2

in which again the value of r 13/3 as stated above.

The epitrochoidial path of the generating point on the periphery of theannular ring is illustrated by FIG. 8, in which a simple cusp occurs ateach end of the short axis and represents an angular change in motionbut not a retrograde motion. Thus the mathematical solution is confirmedby the physical impossibility of such reversal occurring at place ofengagement of the gear teeth. Having obtained the actual K factor forconventional guidance means it is possible to find solutions for allproposed design applications. For example the present generation ofrotary engines is operative with a K factor that usually is about 7 inrespect to the epitrochoidal body, while the guidance system isdiminished in size to make its effective K factor equal to 6.

This problem does not arise with the guidance system of this invention,since the engagement between the guidance members is by sliding engagingsurfaces, which will permit some retrograde motion, as illustrated bythe curve of FIG. 8. It is therefore possible to construct a mechanismin accordance with the invention with a K value lower than 6, which isin itself a substantial design advantage.

An analysis of the rotary engines at present commercially availableshows that all of them have an epitrochoidal chamber of K-factor muchgreater than 6, and the figures which I have been able to obtain appearto show a range of K-factor from about 6.73 to about 7.14. It is atpresent believed that a probable reason for this is that, as isillustrated by FIG. 9, a K factor of 6 represents a unique value for theuniversally used three-lobed rotor and two-lobed stator, which involvesstationary or almost stationary relative motion betwen the rotor andstator at two points in every rotation of the rotor. This theoreticalobservation correlates with the practical observation that as the Kfactor decreases toward the value 6 there is a tendency for the rotor toflutter or chatter, indicating severe instability in its motion. It canbe shown that for a K value of 6 the period of stationary or nearstationary motion can extend over an angle as great as A practicalresult of this particular flutter or chatter instability, besides theobjectionable noise, vibration and possible damage to the bearings, is abreakdown of the lubricating oil film or the stator surface andconsequent scoring and severe damage thereto.

An examination of FIG. 8 will show that, although there are tworeversals of motion in each revolution, these do not involveintermediate instable unique locations, but instead take place smoothlyand progresively. As explained above the gear type guidance means usedhitherto cannot function at a K value other than 6, and therefore it hasnever been possible with such engines to pass beyond this highlyunstable value to the more stable value of 5.

The mechanism illustrated by FIGS. 2 to 5 has a K value of 5 for thestator and, as described, the small circles show the contact locationsfor the guidance surfaces for this value. As explained, although therotor only is being indexed at two locations, being the two locations atwhich reversal of motion takes place, and is being guided at all otherlocations, rotor stability is assured during the entire cycle of eachrotation. If the value of K is 6 or any larger value then the rotor isbeing indexed in all positions thereof.

In general mechanisms in accordance with this invention may employ anyvalue of K factor contained within the range K at infinity to K equal 5,preferably avoiding the apparently uniquely unstable value 6. As apractical matter useful power is concentrated in a limited range where Kis not greater than 10. Also in practical terms the preservation of astable pattern or motion must be sustained. By referring to FIG. 2 and 5it can be seen that there are a maximum of three points of contactbetween the rotating and the fixed surfaces. The positions of the rotorshow that the extreme end points of the fixed guide surface as well asone point on its short axis are in simultaneous contact with surfaces onthe rotor. It can be inferred that this condition confers an exactindexing function on the guidance system which is necessary to preservestability. A limit value for K for mechanisms of this invention can beobtained by solving the general equation for the core guide surface withthe rotor in the position of FIG. 2 or 5. The known relations are thatwhen (1) 7r/3 the value of x 0, where x is the abscissa.

The equation is [(K4)+2 cos 2 4)] (r cos d (UK) and 0 1 -41 thereforeLikewise it can be deduced that stability is also preserved for allother positions, in view of the nature of the general equation, withinthe limits specified, namely that (l) the curve is a continuous functionbetween the ends of its major axis; (2) it has no singular points orinflections between these limits; and (3) it is symmetrical about itsmajor axis. The rotor can be shown to have balanced relationship ofdynamic and mechanical stability, since the path of the rotors centre ofgravity is in uniform circular motion under continuous surveillence oftwo opposed surfaces providing guidance with mechanical exactitude.

The effect of this possible reduction in K factor is illustrated byFIGS. 10 to 16, which show graphs of computations involving four cycleinternal combustion engines of K factors from 5 to 7. In each case thefollowing limits are used to permit direct comparison:

a. Compression ratio is 10 and is constant b. Rotor is measured as anequilateral triangle with sides 2R 2 Vii r c. The rotor short radius isr d. The rotor long radius is 2r,

e. The radius of eccentricity r in terms of K is 2r /K f. Rotor width issubject to designers choice, but for these examples its specific valueis fixed as 3r 61' /K g. Displacement volume V h. Volume of chamber 18absolute volume V i. The equation for V 241rr /K K +3) j. Theequationfor v,, so Vi /x FIG. 10 shows the increase in rotor surfacearea and working stroke, both of which are functions of K, with decreaseof K, while FIG. 11 shows the increase in displacement volume V of therotor (equivalent to piston displacement in a piston engine) compared tothe 9 increase in total available volume in the epitrochoidal chamber18. FIG. 12 combines the results of FIGS.

and I1 and shows that three rotors of K 5 should be capable of the sameoutput as four rotors of K 7.

FIGS. 13 to 16 show the expected performance of engines of the samesize, but having differing K factors. FIG. 13 plots the value of V whichis in this example a constant, the load factors causing friction (whichare found to correspond to V and the relative radii of the rotatingparts. FIG. is a plot of the gross power factor and the value of V is ameasure of this, since the compression ratio is constant. FIG. 15 showsthe friction power loss computed using the factors of FIG. II, and thenet power factor N which is the result of subtracting friction powerloss from gross power. It will be seen that N at K 7 has the relativevalue 1.0, while at K 5 it has become 1.6, so that on this basis tworotors of K 5 should have the net power output of three rotors of K 7.The efficiency factor of an engine is an indication of the power to beobtained from a unit quantity of fuel, and is expressed by the relationN/V A plot of this factor is shown in FIG. 16. The increasing factorshows that increased power is obtained per unit size of engine as K isdecreased from 7 to 5.

At this time I am not aware of any discussion of the problem of anadequate performance rating formula tween different rotary mechanisms.This problem differs from the subject of the comparison of rotarymechanisms with piston type mechanisms, which has been treated indetail. The increased scope for improvement in rotary mechanism designhas disclosed the need for a standard rating formula, which will beadequate as a guide to and a measure of the progress in rotary mechanismdevelopment.

A formula is required to measure the efficiency with which the availablevolume is utilized for useful work. It is a noteworth feature of amechanism in accordance with the invention and of K value 5 thatsubstantially all its internal volume appears to be available for thework cycle, as though its moving parts had vanished. This-entireinternal volume is called Absolute Volume for that reason and is denotedas V The displacement volume must take into account the compressionratio, (denoted by the letter 11) and is termed V The number of powerimpulses is three per rotor revolution. Then Absolute VolumetericEfficiency Ratio is given by:

Using the convention set out above and with n=l0, the tabulation of theratio as a percentage is:

10 in multiples. The engine may be of internal or external combustiontype. The guidance system of this invention may be used in an engine orpump in addition to another system, such as the known gear-type Wankelsystern described above, in order to assist in stabilizing the motion ofthe rotor.

I claim:

1. In a rotary mechanism comprising a body providing an internal chamberhaving an internal peripheral surface and a lobed rotor mounted withinthe chamber for rotation within the chamber with a plurality ofcircumferentially-spaced apex portions in sealing engagement with thesaid chamber internal surface, a seal for interposition between arespective apex portion and the chamber internal surface, each sealcomprising two axially-extending abutting seal members mounted inrespective axially-extending slots in the apex portion,

' which would serve as a standard of comparison beeach seal member beingoperative as a piston within its respective slot as a cylinder, meansfor supplying to the leading seal member operative fluid from therespective rotor trailing face, and for supplying to the trailing sealmember operative fluid from the respective rotor leading face, thesupply of fluid to each seal member urging the respective seal memberradially outwardly from the rotor into engagement with the chamberinternal surface and into engagement with the other seal member tooppose the fluid pressure thereon from the chamber.

2. The invention as claimed in claim 1, wherein means for supplyinglubricating fluid to the said seal comprises a passage leading from therotor interior to a space between the abutting seal members and a ballvalve disposed in the said passage, the valve being operative under theeffect of centrifugal force thereon to open and permit flow oflubricating fluid to the said space also under the effect of centrifugalforce, and being operative under the effect of centripetal force thereonto close and obstruct flow of lubricatiing fluid from the said spacealso under the effect of centripetal force.

3. The invention as claimed in claim 1, wherein the said seal membersare both of boomerang transverse cross-section with their surfacesabutting against one another.

4. The invention as claimed in claim 3, wherein means for supplyinglubricating fluid to the said seal comprises a passage leading from therotor interior to a space between the abutting seal members and a ballvalve disposed in the said passage, the valve being operative under theeffect of centrifugal force thereon to open and permit flow oflubricating fluid to the said space also under the effect of centrifugalforce, and being operative under the effect of centripetal force thereonto close and obstruct flow of lubricating fluid from the said space alsounder the effect of centripetal force.

5. In a rotary mechanism comprising a body providing an internal chamberhaving an internal peripheral surface and a lobed rotor mounted withinthe chamber for rotation within the chamber with a plurality ofcircumferentially-spaced apex portions in sealing engagement with thesaid chamber internal surface, a seal for interposition between arespective apex portion and the chamber internal surface, each sealcomprising two axially-extending abutting seal members mounted inrespective axially-extending slots in the apex portion, wherein meansfor supplying lubricating fluid to the said seal comprises a passageleading from the rotor inforce thereon to open and permit flow oflubricating fluid to the said space also under the effect of centrifugalforce, and being operative under the effect of centripetal force thereonto close and obstruct flow of lubricating fluid and gaseous productsfrom the said space also under the effect of centripetal force.

UNITED STATES PATENT OFFICE CERTIFICATE OF- CORRECTION Patent No.3,920,359 Dated November 18, 1975 Inventor) Herbert Lewis Gray It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 6, lihe 57, the formula "3r 2 (r r should read 1 ----2r 3(r rColumn 8, line 62, the portion of the formula reading "247fr 3 K (K2 3)should read --2441 r (K2 3)/K3-.

Signed and Scaled this Seventh Day Of June 1977 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Arrming Officer (m'rrmissioner oj'Parenrsand, Trademarks UNITED STATES PATENT ()FFICE CERTIFICATE OF CORRECTION3,920,359 November 18th 1975 Patent No Dated Herbert Lewis GRAYInventor(s) It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

In the left hand column of the face page, between lines 3 and 4 insert[73] Assignee: Gray & Bensley Research Corporation, Milton, Ontario,

Canada.

Signed and Scaled this First Day f February 1977 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (ummixsioner of Parentsand Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3,920,359 Dated November 18, 1975 Inventor(s) Herbert LeWlSGray It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

Column 6, line 57 the formula "3r 2 (r r should read.

1 -2r 3(r r Column 8, line 62, the portion of the formula reading"24'77r 3 /K (K 3) should read "2441 r (K 3)/K Signcd and Scaled thisSeventh D a y or June 1977 [SEAL] A ttest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer V Commissioner oflarermand, Trademarks

1. In a rotary mechanism comprising a body providing an internal chamberhaving an internal peripheral surface and a lobed rotor mounted withinthe chamber for rotation within the chamber with a plurality ofcircumferentially-spaced apex portions in sealing engagement with thesaid chamber internal surface, a seal for interposition between arespective apex portion and the chamber internal surface, each sealcomprising two axially-extending abutting seal members mounted inrespective axially-extending slots in the apex portion, each seal memberbeing operative as a piston within its respective slot as a cylinder,means for supplying to the leading seal member operative fluid from therespective rotor trailing face, and for supplying to the trailing sealmember operative fluid from the respective rotor leading face, thesupply of fluid to each seal member urging the respective seal memberradially outwardly from the rotor into engagement with the chamberinternal surface and into engagement with the other seal member tooppose the fluid pressure thereon from the chamber.
 2. The invention asclaimed in claim 1, wherein means for supplying lubricating fluid to thesaid seal comprises a passage leading from the rotor interior to a spacebetween the abutting seal members and a ball valve disposed in the saidpassage, the valve being operative under the effect of centrifugal forcethereon to open and permit flow of lubricating fluid to the said spacealso under the effect of centrifugal force, and being operative underthe effect of centripetal force thereon to close and obstruct flow oflubricatiing fluid from the said space also under the effect ofcentripetal force.
 3. The invention as claimed in claim 1, wherein thesaid seal members are both of boomerang transverse cross-section withtheir surfaces abutting against one another.
 4. The invention as claimedin claim 3, wherein means for supplying lubricating fluid to the saidseal comprises a passage leading from the rotor interior to a spacebetween the abutting seal members and a ball valve disposed in the saidpassage, the valve being operative under the effect of centrifugal forcethereon to open and permit flow of lubricating fluid to the said spacealso under the effect of centrifugal force, and being operative underthe effect of centripetal force thereon to close and obstruct flow oflubricating fluid from the said space also under the effect ofcentripetal force.
 5. In a rotary mechanism comprising a body providingan internal chamber having an internal peripheral surface and a lobedrotor mounted within the chamber for rotation within the chamber with aplurality of circumferentially-spaced apex portions in sealingengagement with the said chamber internal surface, a seal forinterposition between a respective apex portion and the chamber internalsurface, each seal comprising two axially-extending abutting sealmembers mounted in respective axially-extending slots in the apexportion, wherein means for supplying lubricating fluid to the said sealcomprises a passage leading from the rotor interior to a space betweenthe abutting seal members and means to prevent passage of excesslubricating fluid to the said space under gas pressure, and also toprevent return of lubricating fluid and gaseous products through thepassage from the said space, comprises a ball valve disposed in the saidpassage, the valve being operative under the effect of centrifugal forcethereon to open and permit flow of lubricating fluid to the said spacealso under the effect of centrifugal force, and being operative underthe effect of centripetal force thereon to close and obstruct flow oflubricating fluid and gaseous products from the said space also underthe effect of centripetal force.